The present invention relates to a device for supporting the field winding of field spiders with salient poles.
Supporting devices for the field windings of field spiders with salient poles must essentially satisfy three conditions:
(a) the support device must provide a reliable support in relation to the forces acting during operation of the field spider,
(b) the rotor body should not be weakened, if possible, by grooves or bores in which the supporting devices are anchored,
(c) the supporting devices should provide as little resistance as possible to the passage of cooling air within the device.
In a supporting device provided for high-speed low-power current generators, known from DE-AS No. 1,199,871, the supporting member is made V-shaped and comprises two resilient arms. The supporting member is pressed in between the field coils under initial tension of the resilient arms. The free ends of the resilient arms support the member, so as to be self-holding, in relation to the pole shoes projecting beyond the field coils, without any further securing.
Such an arrangement is less suitable, however, for larger machines (particularly for 4-pole machines), because the supporting members, which are now right-angled, can no longer fulfill the supporting function by spring force alone. Additional holding devices, for example a support of the radially inner portion of the supporting member on the rotor body, hamper the (axial) passage of cooling air.
It is therefore a primary object of the present invention to provide a supporting device for a field winding of a field spider satisfying the three conditions mentioned at the beginning with the supporting device further distinguished by a simple and economic construction and by an easy assembly.
The problems of the known prior art are solved in that the supporting member according to the present invention comprises support members which are disposed in pairs. The support members bear at least partially against the two free coil surfaces of each field coil and mutually support one another.
In a particular embodiment the support members are angle members which mutually support one another.
Another solution to the above-mentioned problems according to the present invention includes an embodiment having supporting members which comprise two crossed flat members that bear at least partially against the two free coil faces of each field coil. The flat members are gripped in relation to one another or connected to the pole shoe and/or to the pole body.
Both solutions according to the present invention are distinguished by simple and economic construction and ensure a reliable support of the field coils in relation to the centrifugal forces occurring in operation, without the passage of cooling air being adversely affected to an appreciable extent.
In a first more particular embodiment of the present invention, the angle members are gripped in relation to one another by a pressing device consisting of screw bolts and pressing members. The pressing devices are chamfered in a wedge-shape at the surfaces facing one another. This arrangement has the advantage, in particular, that essentially inevitable manufacturing tolerances of the field coils can be taken into consideration without requiring an adaptation of the supporting members. In addition, a tightening of the supporting device is thereby rendered possible at any time.
In a second particular embodiment of the present invention, radially outer ends of the angle members are connected together by a strut. The strut may be welded in place or may be held in place by appropriately shaped guide rails positioned on the outer faces of the angle members. In both cases, the geometry of the arrangement is such that the outer arms of the angle members are urged apart by the strut.
Still another particular embodiment has the ends of the angle members bent towards one another and gripped in relation to one another either by a connecting piece with an H-section or by a screw bolt. In the case of the connecting piece, the mutually supporting surfaces of the angle members and/or of the connecting piece are chamfered in a wedge-shape. Both alternatives render possible the subsequent tightening of the supporting device.
In yet still another form of embodiment the radially outer ends of the angle members are connected to one another by means of a web. The angle members are gripped in relation to one another by means of a threaded bolt which is supported on the web and on the arms of the angle members.
A particular embodiment of the present invention having crossed flat members, permits two different variants of the mutual supporting of the flat members. These variants include the use of a pressing device or the use of welding or other connection of the crossed flat members to the pole shoes and/or to the pole core.
These and other objects and features of the invention will become apparent from the claims and from the following description when read in conjunction with the accompanying drawings.